SQL COUNT* GROUP BY bigger than,

Question

I want to select the distinct keys with the occurence number, this query seems functionate:

SELECT ItemMetaData.KEY, ItemMetaData.VALUE, count(*) 
FROM ItemM         


        

Answer 1

You should use having with group functions instead of where. E.g.:

select ..., count(*) from ... group by ... having count(*) > 2500;

Answer 2

Here is the explanation: WHERE clause introduces a condition on individual rows; HAVING clause introduces a condition on aggregations.

Use WHERE before GROUP BY and HAVING after GROUP BY. It isn't mandatory, but helpuful in most cases.

SELECT 
       ItemMetaData.KEY, ItemMetaData.VALUE, СOUNT(*) 
FROM  ItemMetaData 
GROUP BY
       ItemMetaData.KEY, ItemMetaData.VALUE
HAVING СOUNT(*) > 2500
ORDER BY СOUNT(*) DESC;

Answer 3

You do not need to use a subquery - simply use a having clause instead of where clause to filter by an aggregated column.

SELECT
ItemMetaData.KEY, ItemMetaData.VALUE, count(*)
FROM ItemMetaData
GROUP BY ItemMetaData.KEY
HAVING count(*) > 2500
ORDER BY count(*) desc

Answer 4

HAVING clause for aggregates

SELECT ItemMetaData.KEY, ItemMetaData.VALUE, count(*) 
FROM ItemMetaData 
Group By ItemMetaData.KEY, ItemMetaData.VALUE
HAVING count(*) > 2500
ORDER BY count(*) desc;